Cytosine deaminase gene as a potential tool for the genetic therapy of colorectal cancer

The bacterial enzyme cytosine deaminase (CD) catalyzes the conversion of 5-fluorocytosine (5-FC) to the lethal 5-fluorouracil (5-FU) and so provides a useful system for selective killing of gene-modified mammalian tumor cells. Cloning of the CD gene from Escherichia coli and expression in human tumor cell lines enabled these cells to convert ³H-labeled 5-FC into ³H-5-FU. Two CD-expressing human tumor cell lines (adenocarcinoma cell line KM12 and glioblastoma cell line T1115) became 200-fold more sensitive to 5-FC than the nonexpressing parental cell lines. At least 90% of the cells are killed within 7 days. CD-expressing cells are able to kill nonexpressing cells when grown in the same culture flask (bystander effect). The CD gene may be used as a suicide system for in situ chemotherapy or as a safety mechanism abrogating the expression of other genes. © 1996 Wiley-Liss, Inc.     

Usefulness of repeated direct intratumoral gene transfer using hemagglutinating virus of Japan-liposome method for cytosine deaminase suicide gene therapy

To investigate the feasibility of repeated gene transfection in suicide gene therapy against human solid tumors by a combination of 5- fluorocytosine (5-FC) and its converting enzyme, cytosine deaminase (CD), we repeatedly transfected the yeast CD gene into the human pancreatic cancer cell line BXPC3 using the hemagglutinating virus of Japan-liposome in a new gene transfer method. The in vivo growth of the s.c. transplanted BXPC3 tumor in nude mice given CD-gene transfection was significantly suppressed by i.p. injection of 5-FC when compared with tumors treated with the control vector. Furthermore, the tumor transfected with the CD gene during a 7-day interval was suppressed much more than that of a single transfection. These results suggest that repeated transfection of the suicide gene together with the combination of 5-FC and the yeast CD gene using the hemagglutinating virus of Japan-liposome gene transfer method may be useful for the treatment of human solid tumors, including pancreatic cancer.     

Intrathecal gene therapy for treatment of leptomeningeal carcinomatosis

Leptomeningeal carcinomatosis occurs occasionally in patients with solid malignancies and carries a poor prognosis despite treatment with systemic chemotherapy and/or radiotherapy. We describe the case of a 43 year old man who presented with leptomeningeal carcinomatosis secondary to malignant melanoma. The patient received intraventricular delivery of NIH3T3 producer cells expressing the thymidine kinase (HSV-Tk1) gene via a retroviral vector followed by intravenous ganciclovir. He experienced abrupt and severe meningeal irritation and hyperpyrexia immediately after injection of the producer cells into the ventricular CSF. Vector producer cells (VPC) survived and were detected by NeoR marker gene expression in the CSF for a week, until a single dose of ganciclovir (GCV) was followed by a decline in the copy number of the NeoR marker gene to undetectable levels over 24 h. This decline upon introduction of ganciclovir suggests effective distribution of ganciclovir to producer cells bearing the HSV-Tk gene. The patient survived 9 months after treatment. Side-effects from the treatment included acute hyperpyrexia which was short-lived and medically manageable.     

Multidisciplinary therapy for treatment of patients with peritoneal carcinomatosis from gastric cancer

There is no standard treatment for peritoneal carcinomatosis (PC) from gastric cancer. A novel multidisciplinary treatment combining bidirectional chemotherapy [neoadjuvant intraperitoneal-systemic chemotherapy protocol (NIPS)], peritonectomy, hyperthermic intraperitoneal chemoperfusion (HIPEC) and early postoperative intraperitoneal chemotherapy has been developed. In this article, we assess the indications, safety and efficacy of this treatment, review the relevant studies and introduce our experiences. The aims of NIPS are stage reduction, the eradication of peritoneal free cancer cells, and an increased incidence of complete cytoreduction (CC-0) for PC. A complete response after NIPS was obtained in 15 (50%) out of 30 patients with PC. Thus, a significantly high incidence of CC-0 can be obtained in patients with a peritoneal cancer index (PCI) ≤ 6. Using a multivariate analysis to examine the survival benefit, CC-0 and NIPS are identified as significant indicators of a good outcome. However, the high morbidity and mortality rates associated with peritonectomy and perioperative chemotherapy make stringent patient selection important. The best indications for multidisciplinary therapy are localized PC (PCI ≤ 6) from resectable gastric cancer that can be completely removed during a peritonectomy. NIPS and complete cytoreduction are essential treatment modalities for improving the survival of patients with PC from gastric cancer.     

腹膜转移癌内科治疗新进展

腹膜转移癌因发现较晚且预后差,目前正成为研究热点。随着细胞减灭术及腹腔热灌注治疗的推广,部分经选择的患者获益。针对不同肿瘤的不同时期,大量的临床研究显示,用药选择、用药时机、用药方法方面均取得进展,尤其是加压腹腔内气溶胶化疗的使用减轻了治疗相关不良反应,并提高了疗效。本文就近年来腹膜转移癌的内科治疗进展进行阐述。     

Cytosine deaminase/5-fluorocytosine gene therapy and Apo2L/TRAIL cooperate to kill TRAIL-resistant tumor cells

The death ligand Apo2L/TRAIL (Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand) eradicates many tumor types while sparing most normal tissues. However, some tumors are resistant to TRAIL. We therefore determined if TRAIL cooperates with cytosine deaminase/5-fluorocytosine (CD/5-FC) gene therapy and investigated the mechanisms involved. Transfection of human LAN-5 neuroblastoma cells with CD rendered the cells (LAN-5-CD) sensitive to 5-FC-induced, caspase-dependent apoptosis. Mediated by caspase-3, CD/5-FC and TRAIL cooperated to induce apoptosis in these TRAIL-resistant cells and to cleave X-linked inhibitor of apoptosis protein (XIAP). In established LAN-5-CD tumors growing subcutaneously in mice, intratumorally applied TRAIL did not decrease tumor growth and systemically administered 5-FC only attenuated tumor growth. In contrast, 5-FC together with TRAIL dramatically decreased tumor growth and eradicated a tumor. Assuming sufficient gene transfer of CD in situ, CD/5-FC with TRAIL may be useful for the therapy of tumors resistant to TRAIL.     

Breakthrough therapy for peritoneal carcinomatosis of gastric cancer: Intraperitoneal chemotherapy with taxanes

The effect of chemotherapy on peritoneal carcinomatosis (PC) of gastric cancer remains unclear. Recently, the intraperitoneal (IP) administration of taxanes [e.g., paclitaxel (PTX) and docetaxel (DOC)] during the perioperative period has shown promising results. Herein, we summarized the rationale and methodology for using IP chemotherapy with taxanes and reviewed the clinical results. IP administered taxanes remain in the IP space at an extremely high concentration for 48-72 h. The drug directly infiltrates peritoneal metastatic nodules from the surface and then produces antitumor effects, making it ideal for IP chemotherapy. There are two types of perioperative IP chemotherapy with taxanes: neoadjuvant intraperitoneal and systemic chemotherapy and sequential perioperative intraperitoneal chemotherapy (SPIC). In SPIC, patients receive neoadjuvant IP chemotherapy and the same regimen of IP chemotherapy after cytoreductive surgery (CRS) until disease progression. Usually, a taxane dissolved in 500-1000 mL of saline at ordinary temperature is administered through an IP access port on an outpatient basis. According to phase I studies, the recommended doses (RD) are as follows: IP DOC, 45-60 mg/m²; IP PTX [without intravenous (IV) PTX], 80 mg/m²; and IP PTX (with IV PTX), 20 mg/m². Phase II studies have reported a median survival time of 14.4-24.6 mo with a 1-year overall survival of 67%-78%. A phase III study comparing S-1 in combination with IP and IV PTX to S-1 with IV cisplatin started in 2011. The prognosis of patients who underwent CRS was better than that of those who did not; however, this was partly due to selection bias. Although several phase II studies have shown promising results, a randomized controlled study is needed to validate the effectiveness of IP chemotherapy with taxanes for PC of gastric cancer.     

Heat-directed suicide gene therapy for breast cancer

Adjuvant hyperthermia can improve treatment outcome for locally recurrent breast cancer (LRBC). Previously, we demonstrated that infection of human breast cancer cells with a recombinant adenovirus expressing beta-galactosidase from the human hsp70b gene promoter (Ad.70b.betagal) results in 50- to 800-fold increases in reporter gene expression following heat treatment (30 minutes at 43 degrees C). Here, we describe a heat-directed suicide gene therapy strategy based on an adenoviral vector (Ad.70b.CDTK) in which expression of the dual prodrug-activating E. coli cytosine deaminase/herpes simplex virus thymidine kinase (CDTK) fusion gene is under the control of the hsp70b promoter. Treatment of T47D and MCF-7 breast cancer cells with mild hyperthermia (43 degrees C/30 minutes) and prodrugs (100 microg/ml 5-fluorocytosine and 10 microg/ml ganciclovir) following infection with Ad.70b.CDTK (10-100 PFU/cell) resulted in 30- to 60-fold decreases in clonogenic survival relative to control cultures treated with heat or prodrugs alone. Clonogenic survival declined even further (up to 240-fold) following heat treatment at 41.5 degrees C for 120 minutes. A decreased clonogenic survival was accompanied by tumor cell apoptosis. These results demonstrate that this combined treatment strategy can be highly effective against heat- and radiation-resistant breast tumor cells and supports the continued development of heat-directed CDTK suicide gene therapy strategies for LRBC.     

Biliary cystadenocarcinoma with peritoneal carcinomatosis

An autopsy report of a patient with a hugh biliary cystadenocarcinoma arising in the right lobe of the liver is presented. The tumor had been though to be benign, but peritoneal carcinomatosis developed 18 months after the operation. Autopsy revealed marked peritoneal dissemination of mucinous adenocarcinoma, apparently a result of peritoneal seeding of hepatic cystadenocarcinoma, which was presumed to be triggered by cyst aspiration performed during the operation. Experience indicates that surgical procedures on cystic liver disease should be carried out carefully, considering the possible existence of malignancy.     

腹腔热灌注化疗治疗结直肠癌腹膜癌

结直肠癌局域性进展可形成腹膜癌,大约10％的患者初诊即发现腹膜癌,有4％～19％的患者在根治术后随访期发生腹膜癌,25％～35％的复发患者以腹膜癌为唯一表现。全身化疗对此类腹膜癌只是姑息性治疗,中位生存期不足6个月。缩瘤术加腹腔热灌注化疗则可清除宏观和微观癌细胞。荷兰癌症中心的Ⅰ、Ⅱ、Ⅲ期临床试验总结分析表明,接受完全缩瘤术加腹腔热灌注化疗者的中位生存期可达42．9个月,1、3、5年生存率分别是95％、56％和43％,明显高于传统治疗方法,已成为英国、法国、意大利、荷兰、西班牙和澳大利亚等国的标准治疗。     

Surgical treatment for peritoneal carcinomatosis from gastric cancer

This review describes the latest surgical treatments for peritoneal carcinomatosis (PC) arising from gastric cancer. Systemic chemotherapy is less effective against PC because of the existence of the blood-peritoneal barrier. Accordingly, perioperative intraperitoneal chemotherapy plus cytoreductive surgery (CRS) is a new trend of multidisciplinary therapy for PC. Intraperitoneally administered drugs penetrate directly into the peritoneal dissemination, resulting in the high loco-regional intensity of drugs.     

腹腔热灌注化疗治疗结直肠癌腹膜癌

结直肠癌局域性进展可形成腹膜癌，大约10％的患者初诊即发现腹膜癌，有4％～19％的患者在根治术后随访期发生腹膜癌，25％～35％的复发患者以腹膜癌为唯一表现。全身化疗对此类腹膜癌只是姑息性治疗，中位生存期不足6个月。缩瘤术加腹腔热灌注化疗则可清除宏观和微观癌细胞。荷兰癌症中心的Ⅰ、Ⅱ、Ⅲ期临床试验总结分析表明，接受完全缩瘤术加腹腔热灌注化疗者的中位生存期可达42．9个月，1、3、5年生存率分别是95％、56％和43％，明显高于传统治疗方法，已成为英国、法国、意大利、荷兰、西班牙和澳大利亚等国的标准治疗。     

Oncolytic virotherapy for ovarian carcinomatosis using a replication-selective vaccinia virus armed with a yeast cytosine deaminase gene

In this study, we assessed the ability of a highly tumor-selective oncolytic vaccinia virus armed with a yeast cytosine deaminase gene to infect and lyse human and murine ovarian tumors both in vitro and in vivo. The virus vvDD-CD could infect, replicate in and effectively lyse both human and mouse ovarian cancer cells in vitro. In two different treatment schedules involving either murine MOSEC or human A2780 ovarian carcinomatosis models, regional delivery of vvDD-CD selectively targeted tumor cells and ovarian tissue, effectively delaying the development of either tumor or ascites and leading to significant survival advantages. Oncolytic virotherapy using vvDD-CD in combination with the prodrug 5-fluorocytosine conferred an additional long-term survival advantage upon tumor-bearing immunocompetent mice. These findings demonstrate that a tumor-selective oncolytic vaccinia combined with gene-directed enzyme prodrug therapy is a highly effective strategy for treating advanced ovarian cancers in both syngeneic mouse and human xenograft models. Given the biological safety, tumor selectivity and oncolytic potency of this armed oncolytic virus, this dual therapy merits further investigation as a promising new treatment for metastatic ovarian cancer.     

Intraperitoneal cisplatin in peritoneal carcinomatosis patients

Cisplatin (100 mg) was given by intraperitoneal infusion to 23 patients with peritoneal carcinomatosis. Eighteen patients had gastric cancer, and five had colorectal cancer. The effects of this therapy were as follows. 1) In gastric cancer patients, the mean survival period was 11.0 months. The cumulative survival rate was superior at the level of statistical significance in comparison with controls. 2) The side effects of this agent given intraperitoneally were mild. In particular, nausea was slightly less than with intravesicular or intraarterial infusion.     

Enhancing VSV oncolytic activity with an improved cytosine deaminase suicide gene strategy

Oncolytic viruses (OVs) are promising therapeutic agents for cancer treatment, with recent studies emphasizing the combined use of chemotherapeutic compounds and prodrug suicide gene strategies to improve OV efficacy. In the present study, the synergistic activity of recombinant vesicular stomatitis virus (VSV)-MΔ51 virus expressing the cytosine deaminase/uracil phosphoribosyltransferase (CD::UPRT) suicide gene and 5-fluorocytosine (5FC) prodrug was investigated in triggering tumor cell oncolysis. In a panel of VSV-sensitive and -resistant cells-prostate PC3, breast MCF7 and TSA, B-lymphoma Karpas and melanoma B16-F10-the combination treatment increased killing of non-infected bystander cells in vitro via the release of 5FC toxic derivatives. In addition, we showed a synergistic effect on cancer cell killing with VSV-MΔ51 and the active form of the drug 5-fluorouracil. Furthermore, by monitoring VSV replication at the tumor site and maximizing 5FC bioavailability, we optimized the treatment regimen and improved survival of animals bearing TSA mammary adenocarcinoma. Altogether, this study emphasizes the potency of the VSV-CD::UPRT and 5FC combination, and demonstrates the necessity of optimizing each step of a multicomponent therapy to design efficient treatment.